The invention relates to a motor vehicle body having an underbody and a wheelhouse, and more specifically to such a body having a reinforced structure adjacent the wheelhouse to increase torsional rigidity.
Several types of motor vehicles (station wagons, hatch-backs, sport utility vehicles, etc.) have no permanent partition dividing the trunk from the passenger compartment, with the result that the trunk can be enlarged by folding the rear seat(s) forward. Some traditional sedans also have folding rear seats to provide a loading opening for an extra-long load carrying space. In the case of vehicles without a rear wall or with a rear wall with loading openings, a hinge effect is formed in the region of the junction between the underbody and the wheelhouse at either side of the vehicle, said hinge effect reducing the torsional rigidity of the entire vehicle body.
For various structural and practical reasons, torsional rigidity is difficult to achieve in this region. Any reinforcement fixed on the inside in the transition between the trunk and passenger compartment reduce the size of the loading opening. Furthermore, the fitting of reinforcements after assembly of the sidewall and underbody requires an additional, subsequent manufacturing step, and therefore increases manufacturing cost.
U.S. Pat. No. 5,829,824 discloses a motor vehicle body in which reinforcing struts extend between the left and right wheelhouses. This makes it possible to deepen the loading compartment itself without reducing the rigidity of the vehicle body. The resulting loading compartment enables relatively large objects to be carried. Here too, however, the reinforcing struts partially obstruct the loading opening of the compartment, and the fitting of the reinforcing struts adds to the manufacturing cost. In addition, the heads of the fasteners used to secure the reinforcing struts are exposed, with the result that said fasteners impair the visual impression and constitute a risk of damaging objects accommodated in the loading compartment.
European Patent No. 0 980 817 A2 discloses a vehicle body structure in which a shock absorber of the vehicle suspension system engages the lower surface of the underbody, with the result that the wheelhouse may be made narrower with a consequent increase in the width of the loading opening. Additional reinforcing or stiffening measures for improving the torsional rigidity in the region of the transition from the underbody to the wheelhouse are not proposed.
Taking the disadvantages described in the prior art as the starting point, the invention is based on the object of increasing the rigidity of a motor vehicle body having a loading opening provided in the region of the rear wheelhouses without having to reduce or otherwise obstruct the cross section of the loading opening.
The problem is solved according to the invention by providing a motor vehicle body comprising an underbody, a longitudinal member connected to an underside of the underbody, a wheelhouse connected to the underbody adjacent an outboard edge thereof and having an inboard surface laterally spaced from the longitudinal member, and a reinforcement disposed below the underbody and connected to the wheelhouse inboard surface and to the longitudinal member. By providing a structural connection between the wheelhouse inboard surface and the longitudinal member, the torsional stiffness of the body structure is greatly improved. Because the reinforcement is located below the underbody, it does not obstruct the loading opening and is not visible to the user of the vehicle.
In a preferred embodiment of the invention disclosed herein, the wheelhouse comprises a tower for accommodating a suspension component (such as a shock absorber or strut), the tower projecting from the inboard surface toward the longitudinal member. Since the tower increases the flexural rigidity of the wheelhouse, placement of the reinforcement adjacent the tower provides additional improvement in stiffness in the area of the wheelhouse and longitudinal member when the motor vehicle body is subjected to torsional strain.
Also in accordance with a preferred embodiment, the longitudinal member has an upward-opening U-shaped cross section, forming a sidewall and a lower surface. At least a portion of the reinforcement is of W-shaped cross-section and bears against the inboard surface of the wheelhouse, the underside of the underbody, and the sidewall and the lower surface of the longitudinal member. By this means, the reinforcement is fastened to as many parts as possible thereby resulting in a good, stable connection. The longitudinal member advantageously has a vertical weld flange in the region of the tower of the wheelhouse, which flange is fastened to an inner surface of the tower.
In an advantageous manner, a cross member is connected to the longitudinal member and extend in an inboard direction therefrom. The reinforcement is then fastened to the longitudinal member and/or the cross member preferably in the region of the junction between the longitudinal member and the cross member. This results in a particularly rigid connecting node between the wheelhouse, the longitudinal member and the cross member, which node directs bending moments of the wheelhouse directly into the cross member (and vice versa).
The W-shaped structure of the reinforcement can be interrupted by a diagonal section extending directly from the lower edge of the wheelhouse to the lower edge of the longitudinal member, which edge is formed at the junction between the sidewall and the lower surface of the longitudinal member. The diagonal section acts as an additional reinforcing measure and supports the lower surface of the wheelhouse directly on the lower surface of the longitudinal member, with the result that the motor vehicle body is stiffened with regard to an additional direction of application of force. Furthermore, the section eliminates the risk of the reinforcement buckling, said risk being caused by the shape of the W-shaped reinforcement.
In the case of a further advantageous refinement, the transversely disposed surface of the wheelhouse is directly connected to the web surface of the reinforcement. The direct connection of the transversely disposed surface of the wheelhouse to the web surface gives rise to an even higher node rigidity of the vehicle body in this region.
A further embodiment makes provision for the inner surface of the wheelhouse to be directly connected to the flange surface of the reinforcement. An arrangement of this type is expedient if the longitudinal member does not have a vertical flange and is directly connected to the inner surface of the wheelhouse. This is the case if, for example, the longitudinal member runs somewhat further inward toward the vehicle center, or there is no longitudinal member in the region of the tower. The task of the longitudinal memberxe2x80x94the rigid connection to the inner surface of the wheelhousexe2x80x94is then taken on by the flange surface of the reinforcement.
The invention will be explained in greater detail below with reference to a preferred exemplary embodiment.